Our goal here is to understand how several candidate viral infections enhance autoimmune disease in multiple sclerosis (EAE) and diabetes disease models (von Herrath and Fujinami). The novel aspects addressed by this PPG are: 1. The hypothesis that viral infections will be able to provide a 'fertile field' for autoaggressive lymphocytes or enhance already pre-existing but sub-clinical autoimmune processes. 2. The detailed mechanistic analysis involving mimicry as well as bystander activation, in particular the understanding of the basic mechanistic aspects of virally triggered presentation of autoantigens and activation of autoaggressive lymphocytes from the APC/immuno-proteasome side (Whitton). The emerging findings will be useful in pursuing the link between viruses and autoimmunity in humans in a more directional/mechanistic way.